In order to explain the occurrence of exponentially decreasing lifetime
distributions, the theory of dynamical systems appeals to the sensitivity
to initial conditions of trajectories visiting a homoclinic
tangle [1]}. Here, the modelling that fits well our observations
implies that exponential distributions arise from some jump random
process [2]}. As soon as the size of the system is much larger
that the minimal flow unit (for which the temporal behaviour inherent in
low dimensional dynamical systems is relevant), a spatiotemporal
perspective becomes in order, and the jumps in question can easily be
associated to the local chaotic dynamics of pieces of streaks and
streamwise vortices involved in the self sustaining process of turbulence [3]}.
This local chaotic dynamics would then be responsible for the wandering of
the global system through some “energy” landscape with wells and saddles.
With system sizes of the order of the elementary pattern cell \(\lambda _x\times \lambda _z\) , this wandering amounts to orientation and/or wavelength
changes. Extending these views to larger systems would then explain
the statistical properties of fluctuating laminar-turbulent patches
observed in the upper transitional range close enough to \(R_{\rm t}\)  [4]}.
